Solvent Extraction of Soybean Oil: Process and Equipment

Soybean oil is not only one of the top three most consumed edible oils globally but also a daily staple for residents in northern China. The extraction processes for soybean oil include pressing and solvent extraction. Due to the high residual oil rate and limited production capacity of pressing, large-scale oil mills predominantly use the solvent extraction method. So, what equipment is involved when investing in a solvent extraction production line for soybean oil?

The oil processing equipment required for solvent extraction of soybean oil can generally be categorized into three types: soybean pretreatment equipment, soybean oil solvent extraction equipment, and soybean oil refining equipment.

 

Pretreatment, Extraction, Refining: The Soybean Oil Processing Stages

Pretreatment Equipment

Before solvent extraction, raw materials must undergo pretreatment, which includes cleaning, stone removal, crushing, flaking, and cooking. The purpose of pretreatment is to remove impurities from the raw materials, disrupt their cellular structure, and adjust moisture and temperature to facilitate better oil extraction. Equipment commonly used at this stage includes vibrating cleaning screens, destoners, crushers, flaking machines, cookers, and other oilseed pretreatment machinery, as well as complete sets of soybean oil solvent extraction equipment.

Solvent Extraction Equipment

In the extraction equipment, oilseeds are thoroughly mixed with a solvent to extract the oil, forming a miscella. The miscella is then subjected to evaporation and stripping, leveraging the difference in boiling points between the oil and the solvent, to vaporize the solvent and separate it from the oil. The solvent vapors are channeled through pipes to condensers for recovery and reuse. After separation from the solvent, crude soybean oil is obtained.

The working stages of soybean solvent extraction equipment include: soybean oil extraction—desolventizing, toasting, drying, and cooling of extracted soybean meal—miscella evaporation—miscella stripping—and solvent recovery.

Refining Equipment

Crude oil contains small amounts of solvents and impurities and cannot be directly consumed. It must be refined into finished edible soybean oil. Refining equipment effectively removes phospholipids, proteins, free fatty acids, moisture, pigments, odorous substances, mechanical impurities, waxes, and other components from the oil, thereby improving its quality, ensuring food safety, and extending its shelf life.

Producing Grade I soybean oil requires six main steps: degumming, deacidification, dehydration, decolorization, deodorization, and dewaxing.